High resolution imaging of lumens and epithelial surfaces of internal organs is required for many different types of diagnostic procedures. Among imaging techniques employed in modern medical practice are X-ray, ultrasound (US), magnetic resonance imaging (MRI), computerized tomography (CT) and positron emission tomography (PET). These methods rely on measuring and recording physical parameters of internal body parts, and transforming these parameters into informative images. These methods require expensive equipment, not all of which is available in many small and medium size medical centers (especially MRI). These diagnostic procedures also require several skilled practitioners (doctors, nurses and operators) to perform the procedure and interpret the image outputs. All of these factors together lead to relatively high costs of such procedures to the medical health insurance system, while their frequency of use is increasing.
Direct visual observation of internal body organs, like blood vessels, the gastrointestinal tract (GI), lungs, pelvis and abdomen, have significant advantages over indirect diagnostic imaging mainly because it allows real time observation, and the possibility of obtaining a sample for histological examination. The most common method of directly examining the upper or lower GI tract, as well as for examining other body cavities, is endoscopy. The physician has a real time image (either directly or via an external monitor) of the surface or lumen under investigation. The picture recorded in the endoscopic procedure is produced by optical and electro-optical instruments that are inserted into the body in the form of a long, semiflexible tube. One disadvantage of endoscopy and similar methods is the requirement of a direct connection (rigid or flexible) from the examined area to the detector system outside of the body. Another disadvantage is that the instrument does not move easily through the body cavities, causing discomfort to the patient and putting him at risk for complications such as bleeding and infection, accompanied by significant inconvenience.
An alternative to endoscopy is a method which employs a wireless vehicle inside the body capable of gathering and transmitting image data to outside the body. Such a method is taught by U.S. Pat. Nos. 4,278,077, 5,217,449, 5,604,531, and 6,240,312 which describe in vivo camera systems for examination of internal body lumens. Such an imaging and transmitting device can be any in vivo vehicle that can transmit information outside the body. The movement of such devices depends on external direct aiming (via endoscope or catheter), or, more commonly, on natural movement such as blood flow or peristaltic motion of the digestive muscles.
Relying on peristaltic bowel movement has an inherent disadvantage. When the vehicle is in the colon, the peristaltic movement occurs only if the colon is filled with some fecal content. However, when the colon is filled or partially filled with feces, the observation capability is dramatically reduced. Emptying the colon before inserting the vehicle significantly reduces the peristaltic bowel movement, therefore limiting the vehicle movement. In addition, relying only on the peristaltic movement restricts the area under observation, especially in large spaces such as the stomach and colon.
Another significant disadvantage of a passively driven in vivo video device is the fact that the capsule is constantly transmitting pictures for as long as it is in the body, even when it is not needed. Such continuous operation is inefficient and consumes a lot of energy.
Furthermore, passive devices have the disadvantage of the lack of control over the movement and general behavior of the device within the body. An external operator cannot easily control such movement, nor can the operator easily manage the behavior of the device within the body. Therefore, the device may enter an undesirable location, and/or otherwise behave in a less than optimal manner for the type of diagnostic procedure which is being performed.